A device of this kind has already been proposed in French Pat. No. 1,037,160. Its click, being pivotable between the locking and unlocking positions, ensures a relatively great recoil when the mainspring has been fully wound, thus keeping the mainspring from working at a degree of wind close to the maximum, i.e., with a rapidly-varying torque. However, this known type of click is a relatively large-sized part, the resilient arm of which extends concentrically to the ratchet-wheel. A support element situated at the rearward end of the resilient arm, i.e., at the end connected to the rigid portion, cooperates with a fixed banking situated outside the peripheral limits of the ratchet-wheel so as to determine the unlocking position, while the outer portion of the click-beak cooperates with a sloping surface which causes it to engage in the toothing of the ratchet-wheel and ensures the locking position. The ratchet-wheel--and consequently the arbor--is locked in such a way that, because of this sloping surface, the click-beak is liable to jam in locking position. Futhermore, since the banking which determines the unlocking position is situated on a level with the toothing of the ratchet-wheel, the angle of displacement of the click, starting from the locking position, is limited by the presence of the crown-wheel, which is permanently engaged with the ratchet-wheel and causes it to be driven during manual winding.
Hence the recoil angle in the known device has a well-defined maximum which is on the order of about 20.degree.. It is now known to be desirable, however, to use mainsprings which are very long and have a low torque so as to improve the running regularity of mechanical watch movements. The use of such springs also makes it desirable to produce clicks having a recoil greater than 20.degree. and capable of reaching up to 300.degree. .
The reduction in size of the known large-recoil clicks, a step facilitating the increase in the angle of recoil, must be accompanied by a reduction in the width of the resilient arm so that the latter may flex easily in unlocking position and, consequently, move the click-beak out of the toothing. Under these conditions, the resilient arm is a delicate element which is liable to be deformed either during fitting or in operation, under the influence of the torque to which it is subjected in locking position.
It is an object of this invention to provide improvements in driving devices of the kind initially mentioned so that they may be produced with a angle of recoil of up to 300.degree. and with a smaller click which is easy to assemble and reliable in operation.
To this end, in the driving device according to the present invention, the bridge comprises a recess in which the click is disposed between the bridge and the ratchet-wheel, and the click further comprises a support element disposed at the free end of the resilient arm and situated within the peripheral limits of the ratchet-wheel, the recess having sides comprising, for determining the locking position, at least a first banking cooperating in the locking position with the support element and a second banking cooperating in the locking position with the beak.